Unsupervised Model Selection for Time-series Anomaly Detection

Anomaly detection in time-series has a wide range of practical applications. While numerous anomaly detection methods have been proposed in the literature, a recent survey concluded that no single method is the most accurate across various datasets. To make matters worse, anomaly labels are scarce and rarely available in practice. The practical problem of selecting the most accurate model for a given dataset without labels has received little attention in the literature. This paper answers this question i.e. Given an unlabeled dataset and a set of candidate anomaly detectors, how can we select the most accurate model? To this end, we identify three classes of surrogate (unsupervised) metrics, namely, prediction error, model centrality, and performance on injected synthetic anomalies, and show that some metrics are highly correlated with standard supervised anomaly detection performance metrics such as the $F_1$ score, but to varying degrees. We formulate metric combination with multiple imperfect surrogate metrics as a robust rank aggregation problem. We then provide theoretical justification behind the proposed approach. Large-scale experiments on multiple real-world datasets demonstrate that our proposed unsupervised approach is as effective as selecting the most accurate model based on partially labeled data.Comment: Accepted at International Conference on Learning Representations (ICLR) 2023 with a notable-top-25% recommendation. Reviewer, AC and author discussion available at https://openreview.net/forum?id=gOZ_pKANaP

A molecular understanding of d-homoestrone-induced G2/M cell cycle arrest in HeLa human cervical carcinoma cells

2-Methoxyestradiol (ME), one of the most widely investigated A-ring-modified metabolites of estrone, exerts significant anticancer activity on numerous cancer cell lines. Its pharmacological actions, including cell cycle arrest, microtubule disruption and pro-apoptotic activity, have already been described in detail. The currently tested d-ring-modified analogue of estrone, d-homoestrone, selectively inhibits cervical cancer cell proliferation and induces a G2/M phase cell cycle blockade, resulting in the development of apoptosis. The question arose of whether the difference in the chemical structures of these analogues can influence the mechanism of anticancer action. The aim of the present study was therefore to elucidate the molecular contributors of intracellular processes induced by d-homoestrone in HeLa cells. Apoptosis triggered by d-homoestrone develops through activation of the intrinsic pathway, as demonstrated by determination of the activities of caspase-8 and -9. It was revealed that d-homoestrone-treated HeLa cells are not able to enter mitosis because the cyclin-dependent kinase 1-cyclin B complex loses its activity, resulting in the decreased inactivation of stathmin and a concomitant disturbance of microtubule formation. However, unlike 2-ME, d-homoestrone does not exert a direct effect on tubulin polymerization. These results led to the conclusion that the d-homoestrone-triggered intracellular processes resulting in a cell cycle arrest and apoptosis in HeLa cells differ from those in the case of 2-ME. This may be regarded as an alternative mechanism of action among steroidal anticancer compounds

A diabetes hatása a terhes patkány uterus működésére és farmakológiai reaktivitására = The effect of diabetes on the function and pharmacological reactivity of the pregnant rat uterus

A diabetes mellitus (DM) egyike a leggyakoribb terhességi komplikációknak, jelentős anyai és magzati kockázati tényező. Ugyanakkor kevés adat áll rendelkezésre a DM uterus funkciókra gyakorolt hatásával kapcsolatban. Jelen munkánk célja a streptozotocinnal kiváltott DM mymetriális következményeinek feltárása volt patkányban, a gesztációs kor függvényében. Szuperfúziós technikát alkalmazva azt találtuk, hogy DM-ban jelentősen gyorsul az uterus adrenerg denervációja, ami csökkent noradrenalin felvevő kapacitásban nyilvánul meg. A diabetes posztszinaptikus hatásainak leírására kontraktilitási méréseket végeztünk izolált uterusgyűrűkön. Nem terhes állatban a DM fokozza az ?-, és csökkenti a ?-adrenerg stimulációra adott kontrakciós, ill. relaxációs választ. E változásokat részben magyarázza az ?1B-receptorok DM hatására fokozódó mRNS szintű expressziója, amit RT-PCR technikával mutattunk ki. A terhesség alatt nem találtunk jelentős DM-függő eltérést az uterus motoraktivitásában. Megállapítottuk továbbá, hogy DM esetén fokozódik az exogén oxytocin uterotonikus hatása a gesztáció 15. és 21. napján, mely különbség a terminusra (22. nap) megszűnik. Igazoltuk, hogy DM hatására fokozódik a myometriális oxytocin receptorok expressziója. Eredményeinkből valószínűsíthető, hogy ? hasonló humán viszonyok esetén ? a diabetessel szövődött terhességek fokozott koraszülési kockázatának elhárítására az oxytocin-antagonisták lehetnek a legalkalmasabbak. | Diabetes mellitus (DM) is one of the most frequent complications during pregnancy being a significant fetal and maternal risk factor. However our knowledge concerning the effects of DM on uterine functions is limited. The aim of the present work was to elucidate the myometrial consequences of the streptozotocin-induced DM as a function of gestational age of the rat. The results of superfusion experiments revealed that DM increases the adrenergic denervation of the uterus evidenced by a decreased nordrenaline utake capacity . The postsynaptic effects of DM were characterized by recording the contractility of isolated uterine rings exposed to sympathomimetics. DM resulted in an increase in alpha-receptor-mediated contractions and a decrease in relaxation elicited by terbutaline on non-pregnant uterine rings. These changes could be partly explained by a higher myometrial level of PCR-product of alpha1B-receptor No DM-related change in uterine reactivity was described during pregnancy. Additionally, a more pronounced effect of oxytocin was evidenced in late pregnancy (days 15 and 21) which was diminished by term (day 22). Higher level of oxytocin receptors was detected from the uterine samples of diabetic animals. Presuming similar human regulatory mechanisms, it could be suggested that oxytocin antagonists are drugs of choice for the treatment of DM-elicited risk for premature delivery